Circuit breakers typically provide automatic current interruption to a monitored circuit when undesired overcurrent conditions occur. These overcurrent conditions include, for example, overloads, ground faults, and short-circuits. An overcurrent is usually detected when the fault current generates sufficient heat in a strip composed of a resistive element or bimetal to cause the strip to deflect. The deflection triggers a trip assembly that includes a spring-biased latch mechanism to force a movable contact attached to a movable blade away from a stationary contact, thereby breaking the circuit. The strip is typically coupled to a heater which conducts the current-generated heat to the strip in a known manner. The current (within a predetermined threshold) at which the trip assembly is just prevented from acting yields the current rating for the circuit breaker. When the circuit is exposed to a current above that level for a predetermined period of time, the trip assembly activates and tripping occurs thereby opening the circuit.
The circuit breaker includes a line end and a load end, both of which include lug assemblies to attach conductive cable to supply electrical current to various loads in the electrical circuit. The load lug assemblies contains a load terminal assembly, and consists of a lug body and a lug screw. The lug screw tightens to hold the conductive cable within the lug body. As the lug screw is tightened, the conductive cable is compressed, and an electrical connection is established between the load terminal assembly and the conductive cable.
However, as the lug is tightened onto the conductive cable, the rotational force, or torque, that is applied to the lug also exerts a force onto the main load terminal. When a high torque is applied to the main load terminal, it is permanently deformed at its bends. This can change its position, which effects the calibration of the tripping system.
Another disadvantage to the above approach is that for as the torque is applied to the lug, it is also transferred onto the circuit breaker base. This force can sometimes be high enough to cause cracking and breaking of the circuit breaker base.